Power distribution unit having contactor with integrated pre-charge circuit

ABSTRACT

A power distribution unit includes a housing, a main contactor in a main cavity of the housing, and a pre-charge assembly in a secondary cavity of the housing. The main contactor includes first and second fixed contacts and a movable contact configured to electrically connect the first and second fixed contacts in a mated position. The main contactor includes a coil assembly energized to move the movable contact. The pre-charge assembly includes a pre-charge resistor and a pre-charge switch coupled to the pre-charge resistor. The power distribution unit includes a controller received in the housing. The controller includes a main contactor driver for powering the main contactor and a pre-charge driver for powering the pre-charge switch.

BACKGROUND OF THE INVENTION

The subject matter herein relates generally to power distribution units.

Certain electrical applications, such as HVAC, power supply,locomotives, elevator control, motor control, aerospace applications,electric vehicles, hybrid electric vehicles, fuel-cell vehicles,charging systems, and the like, utilize electrical contactors to controlpower distribution for the devices. For example, vehicles using ahigh-voltage battery pack generally include a main contactor to switchbattery power to the power electronic components. There is generallysome capacitance associated with the power electronics circuitry. Thiscapacitance can create large inrush currents when closing the maincontactor. These large inrush currents can create an arc across thecontacts causing damage to or reducing the operating life of thecontacts and creating sparks. To eliminate the large inrush currents andto protect the main contactor, a pre-charge circuit is often used withthe main contactor.

A typical pre-charge circuit includes a pre-charge contactor in serieswith a pre-charge resistor. During power-up of the vehicle, thepre-charge contactor is closed and current flows through the pre-chargecontactor and the pre-charge resistor. When a desired voltage isreached, the main contactor may be switched on and the pre-chargecontactor may be switched off. The various components of conventionalpower distribution units are grouped together and electrically connectedtogether using wires and bus bars. For example, the individualcomponents are separately mounted to a common frame, such as usingfasteners. Wires are coupled between the components, such as usingterminals, contacts or connectors between the various components.Assembly of the power distribution unit is time consuming, requiringseparate mechanical and electrical connections for each of thecomponents. Additionally, the many components occupy a significant spacewithin the vehicle.

A need remains for a power distribution unit that may be assembled in acost effective and reliable manner.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with embodiments herein, a power distribution unit isprovided. The power distribution unit includes a housing having wallsdefining a main cavity and a secondary cavity. The power distributionunit includes a main contactor received in the main cavity of thehousing. The main contactor includes first and second fixed contacts anda movable contact movable between a mated position and an unmatedposition. The movable contact engages the first and second fixedcontacts to electrically connect the first and second fixed contacts inthe mated position. The movable contact is separated from the first andsecond fixed contacts in the unmated position. The main contactorincludes a coil assembly energized to move the movable contact betweenthe unmated position and the mating position. The power distributionunit includes a pre-charge assembly received in the secondary cavity ofthe housing. The pre-charge assembly includes a pre-charge resistor anda pre-charge switch coupled to the pre-charge resistor. The powerdistribution unit includes a controller received in the housing. Thecontroller includes a main contactor driver for powering the maincontactor. The controller includes a pre-charge driver for powering thepre-charge switch.

In another embodiment, a power distribution unit is provided. The powerdistribution until includes a housing having walls defining a maincavity and a secondary cavity. The power distribution until includes amain contactor received in the main cavity of the housing. the maincontactor includes first and second fixed contacts and a movable contactmovable between a mated position and an unmated position. The movablecontact engages the first and second fixed contacts to electricallyconnect the first and second fixed contacts in the mated position. Themovable contact is separated from the first and second fixed contacts inthe unmated position. The main contactor includes a coil assemblyenergized to move the movable contact between the unmated position andthe mating position. The power distribution until includes a pre-chargeassembly received in the secondary cavity of the housing. The pre-chargeassembly includes a pre-charge resistor and a pre-charge switch coupledto the pre-charge resistor and configured to be coupled to a pre-chargecapacitor. The power distribution until includes a controller receivedin the housing. The controller includes a trigger connector electricallycoupled to a control circuit board. The trigger connector is configuredto receive a trigger signal from a vehicle controller. The controllerincludes a main contactor driver for powering the main contactor. Thecontroller includes a pre-charge driver for powering the pre-chargeswitch. The controller includes a microcontroller operably coupled tothe main contactor driver and operably coupled to the pre-charge driver.The controller activates the pre-charge driver upon receiving thetrigger signal to charge the pre-charge capacitor prior to activatingthe main contactor driver.

In a further embodiment, a vehicle battery system is provided. Thevehicle battery system includes a high voltage battery pack having apositive battery terminal and a negative battery terminal. The vehiclebattery system includes an inverter configured to convert DC power fromthe high voltage battery pack to AC power for operating an electricmotor of a vehicle. The vehicle battery system includes a powerdistribution unit between the high voltage battery pack and theinverter. The power distribution unit includes a housing having wallsdefining a main cavity and a secondary cavity. The power distributionunit includes a main contactor received in the main cavity of thehousing. The main contactor includes first and second fixed contacts anda movable contact movable between a mated position and an unmatedposition. The movable contact engages the first and second fixedcontacts to close the main contactor and electrically connect the highvoltage battery pack with the inverter. The movable contact is separatedfrom the first and second fixed contacts in the unmated position to openthe main contactor. The main contactor includes a coil assemblyenergized to move the movable contact between the unmated position andthe mating position. The power distribution unit includes a pre-chargeassembly received in the secondary cavity of the housing. The pre-chargeassembly includes a pre-charge resistor and a pre-charge switch coupledto the pre-charge resistor and configured to be coupled to a pre-chargecapacitor. The power distribution unit includes a controller received inthe housing. The controller is configured to receive a trigger signalfrom a vehicle controller. The controller includes a main contactordriver for powering the main contactor. The controller includes apre-charge driver for powering the pre-charge switch. The controllerincludes a microcontroller operably coupled to the main contactor driverand operably coupled to the pre-charge driver. The controller activatesthe pre-charge driver upon receiving the trigger signal to charge thepre-charge capacitor prior to activating the main contactor driver.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a vehicle having a powerdistribution unit in accordance with an exemplary embodiment.

FIG. 2 is a diagram of the power distribution unit of a vehicle batterysystem in accordance with an exemplary embodiment.

FIG. 3 is an exploded view of the power distribution unit in accordancewith an exemplary embodiment.

FIG. 4 is a perspective view of the power distribution unit inaccordance with an exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration of a vehicle 10 having a powerdistribution unit 100 in accordance with an exemplary embodiment. Thevehicle 10 may be an electric vehicle. In other various embodiments, thevehicle 10 may be a hybrid electric vehicle, such as including an engine(not shown). The vehicle 10 includes one or more electric motors 12 fordriving wheels 14 of the vehicle 10. An inverter 16 is provided forcontrolling power to the electric motor 12.

The vehicle 10 includes a vehicle battery system 18 for supplying powerfor the vehicle 10, such as for the electric motor 12 or other vehiclesystems or components. The power distribution unit 100 is part of thevehicle battery system 18. The vehicle battery system 18 includes abattery pack 20, such as a high voltage battery pack 20 for powering theelectric motor 12. The battery pack 20 provides a high voltage DCoutput. The battery pack 20 is electrically connected to the powerdistribution unit 100. The power distribution unit 100 is alsoelectrically connected to the electric motor 12. In addition toproviding energy for the electric motor 12, the battery pack 20 mayprovide energy for other vehicle electrical systems, such as forheaters, compressors, low voltage DC components, and the like. Thevehicle battery system 18 may include other system components, such as aDC-to-DC converter. The electric motor 12 may operate as a generator torecharge the battery pack 20 to provide fuel economy benefits and reducepollutant emissions.

The power distribution unit 100 is provided between the battery pack 20and the inverter 16. The power distribution unit 100 controls powersupply between the battery pack 20 and the inverter 16. The powerdistribution unit 100 includes a main contactor 102 and a pre-chargeassembly 104 integrated with the main contactor 102. The main contactor102 is an electrical switch or relay that safely connects anddisconnects one or more electrical circuits to protect the flow of powerthrough the system. The precharge assembly is used for pre-charging acapacitor of the vehicle battery system 18 and includes an electricalswitch or relay and resistor that safely pre-charges the capacitor. Thepower distribution unit 100 may be used in other various applicationsother than the vehicle, such as HVAC, power supply, locomotives,elevator control, motor control, aerospace applications, chargingsystems, and the like.

In an exemplary embodiment, the vehicle 10 includes a vehicle controller40 electrically coupled to the power distribution unit 100. The vehiclecontroller 40 sends trigger signals to the power distribution unit 100for operating the power distribution unit 100. The power distributionunit 100 controls the power supply to the inverter 16. For example, thepower distribution unit 100 includes drivers for opening and closingswitches to supply power to the inverter 16. The drivers are operatedbased on the trigger signals from the vehicle controller 40. In anexemplary embodiment, multiple switches are operated based on a singletrigger signal transmitted from the vehicle controller 40 to the powerdistribution unit 100. The trigger signals may be based on a request forbattery power, such as turning a key or pressing a start button on thevehicle 10, plugging in a charger, such as a phone charger, operatinganother vehicle system, such as the heating/cooling system of thevehicle 10, or other request for vehicle power.

FIG. 2 is a diagram of the power distribution unit 100 of the vehiclebattery system 18. The power distribution unit 100 is electricallyconnected between the battery pack 20 and a load 30, such as theinverter 16 for the electric motor 12. The vehicle battery system 18includes a positive circuit 32 and a negative circuit 34. The positivecircuit 32 is coupled to a positive battery terminal 22 of the batterypack 20. The negative circuit 34 is coupled to a negative batteryterminal 24 of the battery pack 20. The main contactor 102 and thepre-charge assembly 104 of the power distribution unit 100 areelectrically coupled to the positive circuit 32. A negative contactor 36is coupled to the negative circuit 34. A capacitor 38 is coupled betweenthe positive circuit 32 and the negative circuit 34.

In an exemplary embodiment, the main contactor 102 may default to anopen position such that the battery pack 20 is disconnected from theload 30. In the open position, the battery pack 20 cannot provide powerto the load 30. A signal or request to close the main contactor 102 maybe issued by the vehicle controller 40, such as in response to anignition on request by the driver or other event, such as a chargerbeing connected or whenever it is required for the battery pack 20 to beconnected to other devices. The power distribution unit 100 includes acontroller 240 for controlling power supply through the powerdistribution unit 100. The controller 240 includes a main contactordriver 242 to control opening and closing of the main contactor 102. Thecontroller 240 includes a pre-charge driver 244 to control opening andclosing of the pre-charge assembly 104. Communication of the open andclose signals may be via a discrete signal connector or serialcommunications bus connection between the vehicle controller 40 and thecontroller 240 of the power distribution unit 100. The pre-chargeassembly 104 is used to charge the capacitor 38 prior to closing themain contactor 102. The pre-charge assembly 104 is activated prior tothe main contactor 102 to charge the capacitor 38 prior to activatingthe main contactor 102. For example, the controller activates thepre-charge driver 244 prior to activating the main contactor driver 242,such as a predetermined time before activating the main contactor driver242 (for example, approximately 100 ms). The pre-charge assembly 104minimizes inrush current through the main contactor 102 when the maincontactor 102 is switched on by minimizing the voltage difference. Thepre-charge assembly reduces or eliminates problems with closing the maincontactor 102 due to the large inrush current. For example, thepre-charge assembly 104 may reduce arcing across the main contactor 102during switching. The current flowing through the pre-charge assembly104 may be limited to a value substantially less than a rated currentfor the load being pre-charged. For example, the current may be limitedto a value of 5 Amps or less while the rated load current may behundreds of amps. Limiting the current affects the rate of voltageincrease of the load 30. The time required for the capacitor 38 tocharge may be set to a predetermined amount of time, such asapproximately 100 ms. In an exemplary embodiment, the controller 240controls the pre-charge sequence and takes the control responsibilityaway from the vehicle controller 40. Taking the responsibility away fromthe vehicle controller 40 reduces the overhead of the main electroniccontrol unit of the vehicle. The controller 240 controls the sequence ofclosing the pre-charge switch allowing the capacitor 38 to charge. Thecontroller 240 monitors the capacitor charge to control opening of thepre-charge switch and to control closing of the main contactor 102. Thecontroller 240 may use control algorithms to determine when thecapacitor has enough charge (for example, based on timing or based oncurrent sensing). When the capacitor 38 has sufficient charge, thecontroller 240 energizes the main contactor 102 and turns off thepre-charge switch. The controller 240 protects the main contactor 102from damage.

The pre-charge assembly 104 is placed in parallel with the maincontactor 102. One side of the pre-charge assembly 104 is electricallyconnected to the battery pack 20. Another side of the pre-chargeassembly 104 is electrically connected to the capacitor 38 and the load30. The controller 240 of the pre-charge assembly 104 controls operationof the pre-charge assembly 104, such as providing control signals toactivate the pre-charge assembly 104 and to activate the main contactor102 after the capacitor 38 is charged. The control signal may be asignal to control a switching device (e.g., gate drive of a MOSFET). Thecontrol signal may be a voltage or current applied to the switchingdevice. The control signal may be a voltage or current applied to a coilassembly.

FIG. 3 is an exploded view of the power distribution unit 100 inaccordance with an exemplary embodiment. The power distribution unit 100includes a housing 106 holding the main contactor 102, the pre-chargeassembly 104, and the controller 240. The housing 106 includes walls 108forming a main cavity 110 and a secondary cavity 112. The main cavity110 holds the main contactor 102 and the secondary cavity 112 holds thepre-charge assembly 104. The main cavity 110 and the secondary cavity112 are both integrated within the common housing 106. The housing 106is a single-piece housing with the walls 108 forming the main cavity 110and the walls 108 forming the secondary cavity 112 being co-molded as asingle, unitary, monolithic structure. In the illustrated embodiment,the main cavity 110 has a circular cross-section and the secondarycavity has a rectangular cross-section; however, the cavities may haveother shapes in alternative embodiments.

In an exemplary embodiment, one of the walls 108 of the housing 106 is aseparating wall 114 located between the main cavity 110 and thesecondary cavity 112. The separating wall 114 defines a portion of themain cavity 110 and a portion of the secondary cavity 112. A first sideof the separating wall 114 faces the main cavity 110 and a second sideof the separating wall 114 faces the secondary cavity 112. The housing106 includes mounting flanges 116, such as at the bottom, configured tobe mounted to a structure within the vehicle 10.

The housing 106 includes a lid 118 for closing the main cavity 110 and acover 119 for covering the secondary cavity 112. Optionally, the lid 118and/or the cover 119 may be sealed to the walls 108 of the housing 106.

The power distribution unit 100 includes fixed contacts 120 received inthe main cavity 110 and a movable contact 122 movable within the maincavity 110 between a mated position and an unmated position. The movablecontact 122 engages the fixed contacts 120 to electrically connect thefixed contacts 120 in the mated position. The fixed contacts 120 arefixed to the housing 106. For example, the fixed contacts 120 may becoupled to a contact holder 124 received in the main cavity 110. Thecontact holder 124 includes openings 126 that receive the fixed contacts120. The contact holder 124 defines an enclosure 128. The fixed contacts120 extend into the enclosure 128. The movable contact 122 is receivedin the enclosure 128 and configured to engage the fixed contacts 120when the main contactor 102 is operated.

The fixed contacts 120 each include a terminating end 130 and a matingend 132. The terminating end 130 is configured to be terminated toanother component, such as a wire or a busbar, such as a line in or aline out busbar. In an exemplary embodiment, the terminating end 130 isexposed at the exterior of the power distribution unit 100 forterminating to the other component. The terminating end 130 may bethreaded to receive a nut. In the illustrated embodiment, theterminating end 130 extends through the lid 118 and is located above thelid 118. The mating end 132 is located within the main cavity 110 formating engagement with the movable contact 122, such as when the powerdistribution unit 100 is energized. In the illustrated embodiment, themating end 132 is generally flat for engaging the movable contact 122.However, the mating end 132 may have other shapes in alternativeembodiments, such as a rounded shape to form a mating bump at the matingend 132 for mating with the movable contact 122.

The power distribution unit 100 includes a coil assembly 140 in the maincavity 110 operated to move the movable contact 122 between the unmatedposition and the mated position. The coil assembly 140 includes awinding or coil 142 wound around a core 144 to form an electromagnet.The coil assembly 140 includes a plunger 146 coupled to the core 144.The movable contact 122 is coupled to the plunger 146 and is movablewith the plunger 146 when the coil assembly 140 is operated. The coilassembly 140 includes a spring 148 for returning the movable contact 122to the unmated position when the coil assembly 140 is deenergized. In anexemplary embodiment, the coil assembly 140 includes an outer core 150configured to be received in the main cavity 110. The coil 142 isconfigured to be received in the outer core 150.

In an exemplary embodiment, the power distribution unit 100 includes anarc suppressor 152 for suppressing electrical arc of the electricalcircuit. The arc suppressor 152 is located in the cavity 110 of thehousing 106. Optionally, the arc suppressor 152 may be located in thecontact holder 124, such as in or near the enclosure 128. In anexemplary embodiment, the arc suppressor 152 includes magnets creatingmagnetic fields in the enclosure 128 for suppressing arc created betweenthe movable contact 122 and the fixed contacts 120. In an exemplaryembodiment, the contact holder 124 may be sealed and may be filled withan inert gas for arc suppression.

The housing 106 holds the components of the power distribution unit 100.The housing 106 includes a first end 160 and a second end 162 oppositethe first end 160. The first end 160 may be a top of the housing 106 andthe second end 162 may be a bottom of the housing 106. The housing 106includes a first side 164 and a second side 166 opposite the first side164. The main cavity 110 is provided at the first side 164. Thesecondary cavity 112 is provided at the second side 166. In theillustrated embodiment, the main cavity 110 is open at the first end160. The main cavity 110 receives the main contactor 102 through theopen first end 160. The lid 118 is coupled to the housing 106 at thefirst end 160 to close the main cavity 110. In the illustratedembodiment, the secondary cavity 112 is open at the second side 166. Thesecondary cavity 112 receives the pre-charge assembly 104 through theopen second side 166. In an exemplary embodiment, the secondary cavity112 holds the controller 240. The cover 119 is coupled to the housing106 at the second side 166 to enclose the pre-charge assembly 104 in thesecondary cavity 112 and retain the pre-charge assembly 104 in thesecondary cavity 112. The pre-charge assembly 104 is housed in the samehousing 106 with the main contactor 102. The controller 240 is housed inthe same housing 106 with the main contactor 102. The power distributionunit 100 does not require a second housing for the pre-charge assembly104 or the controller 240, thus reducing part count and assembly time.

The lid 118 is configured to be coupled to the housing 106 at the firstend 160. The lid 118 includes openings 170 that receive the fixedcontacts 120. The openings 170 are aligned with the openings 126. Thelid 118 is shaped to fit in the housing 106, such as in the main cavity110. The lid 118 is manufactured from a dielectric material, such as aplastic material. In an exemplary embodiment, the lid 118 includes anisolator 172 having isolating walls 174 configured to electricallyisolate the terminating ends 130 of the fixed contacts 122. The isolator172 is manufactured from a dielectric material, such as a plasticmaterial.

In an exemplary embodiment, the housing 106 includes contact channels180 between the main cavity 110 and the secondary cavity 112. Thecontact channels 180 are located in the separating wall 114 in theillustrated embodiment. The contact channels 180 allow contacts to passbetween the main cavity 110 and the secondary cavity 112.

The pre-charge assembly 104 is received in the secondary cavity 112. Thepre-charge assembly 104 includes a control circuit board 200, one ormore pre-charge resistors 202 coupled to the control circuit board 200,and a pre-charge switch 204 coupled to the control circuit board 200.The control circuit board 200 forms a portion of the controller 240. Forexample, the pre-charge assembly 104 is integrated with the controller240.

The controller 240 includes the main contactor driver 242 to control themain contactor 102 and the pre-charge driver 244 to control thepre-charge assembly 104. The controller 240 includes a microcontroller246 for controlling the main contactor driver 242 and the pre-chargedriver 244. The microcontroller 246 may be an integrated circuit (IC)designed to govern specific operation of the main contactor driver 242and the pre-charge driver 244. The microcontroller 246 may include aprocessor, a memory and input/output (I/O) peripherals on a single chip.The microcontroller 246, the main contactor driver 242 and thepre-charge driver 244 may be surface mounted to the control circuitboard 200. For example, the main contactor driver 242 and the pre-chargedriver 244 may be soldered to pads on the control circuit board 200. Thecontrol circuit board 200 supports the microcontroller 246, the maincontactor driver 242 and the pre-charge driver 244 in the secondarycavity 112. In other various embodiments, the main contactor driver 242and/or the pre-charge driver 244 may be integrated with themicrocontroller 246 on a single chip. In various embodiments, thecontroller 240 may include an A-to-D converter for converting betweenanalog signals and digital signals, such as for controlling the maincontactor driver 242 and the pre-charge driver 244.

In an exemplary embodiment, the controller 240 includes a triggerconnector 248 electrically coupled to the control circuit board 200. Thetrigger connector 248 is configured to receive a trigger signal from thevehicle controller 40 (shown in FIG. 1). For example, an electricalconnector may be coupled to the trigger connector 248. The triggerconnector 248 may be a plug connector or a receptacle connector invarious embodiments. The trigger signals are used by the controller 240to operate the main contactor driver 242 and the pre-charge driver 244.For example, the trigger signals are used to activate the pre-chargedriver 244 upon receiving the trigger signal to charge the pre-chargecapacitor 38 prior to activating the main contactor driver 242.

In an exemplary embodiment, the pre-charge switch 204 is a semiconductorswitch. For example, the pre-charge switch 204 may be a MOSFET. In othervarious embodiments, the pre-charge switch 204 may be a triac or aninsulated-gate bipolar transistor (IGBT). In other various embodiments,the pre-charge switch may be a mechanical relay. The pre-charge switch204 is coupled to a first side 206 of the control circuit board 200. Thepre-charge resistors 202 are coupled to a second side 208 of the controlcircuit board 200. However, in alternative embodiments, the pre-chargeswitch 204 and the pre-charge resistors 202 may be coupled to the sameside of the control circuit board 200. The pre-charge switch 204 and thepre-charge resistors 202 may be surface mounted to the control circuitboard 200. For example, the pre-charge switch 204 and the pre-chargeresistors 202 may be soldered to pads on the control circuit board 200.The control circuit board 200, pre-charge resistors 202, and pre-chargeswitch 204 are loaded into the secondary cavity 112 of the housing 106and secured in the secondary cavity 112 by the cover 119. The controlcircuit board 200 supports the pre-charge resistors 202 and thepre-charge switch 204 in the secondary cavity 112. The walls 108 of thehousing 106 and the cover 119 enclose the pre-charge assembly 104.Optionally, a seal may be provided between the cover 119 and the housing106.

The power distribution unit 100 includes first and second pre-chargeconnection terminals 210, 212. The first and second pre-chargeconnection terminals 210, 212 are received in the corresponding contactchannels 180. The first and second pre-charge connection terminals 210,212 each extends between a first end 214 and a second end 216. The firstend 214 is coupled to the corresponding fixed contact 120. For example,the first end 214 may include a ring 218 that receives the terminatingend 130. A nut may couple the first end 214 to the fixed contact 120. Awire or busbar is configured to be terminated to the terminating end 130of the fixed contact 120 and/or the first end 214 of the pre-chargeconnection terminal 210, 212. The second end 216 is coupled to thecontrol circuit board 200. For example, the second end 216 may include apin or tail configured to be press-fit into the control circuit board200. The first and second pre-charge connection terminals 210, 212supply power to a power circuit of the control circuit board 200 and thepre-charge driver 244. The pre-charge driver 244 is operated to supplythe power to the pre-charge switch 204. The pre-charge switch 204 iselectrically connected to the fixed contacts 120 by the pre-chargeconnection terminals 210, 212 without wires therebetween. Assembly ofthe power distribution unit 100 is quick and easy without the need forconnecting individual wires or busbars between the various components.The pre-charge connection terminals 210, 212 are quickly and easilycoupled to the fixed contacts 120 to supply power to the pre-chargeassembly 104. For example, a voltage or current may be used to activatethe pre-charge switch 204.

The power distribution unit 100 includes coil connection terminals 220.The coil connection terminals 220 are received in the correspondingcontact channels 180. The coil connection terminals 220 each extendsbetween a first end 224 and a second end 226. The first end 224 iscoupled to the coil 142. The second end 226 is coupled to the controlcircuit board 200. The coil connection terminals 220 are electricallyconnected to the power circuit of the control circuit board 200. Themain contactor driver 242 is activated to supply power to the coil 142to operate the main contactor 102. The coil assembly 140 is operated byan output from the main contactor driver 242 transmitted on the coilconnecting terminals 220. For example, a voltage or current may betransmitted on the coil connecting terminals 220 to activate the coilassembly 140.

FIG. 4 is a perspective view of the power distribution unit 100 inaccordance with an exemplary embodiment. When assembled, the maincontactor 102 is received in the housing 106 and the pre-charge assembly104 is received in the housing 106. The controller 240 is received inthe housing 106 to operate the main contactor 102 and the pre-chargeassembly 104. The lid 118 closes the main contactor 102 in the maincavity 110. The cover 119 closes the controller 240 and the pre-chargeassembly 104 in the secondary cavity 112. The fixed contacts 120 areexposed at the first end 160 for connection to power wires or busbars.The single connection supplies power to both the main contactor 102 andthe pre-charge assembly 104.

The controller 240 controls power supply to the pre-charge switch 204and the coil assembly 140. For example, the controller 240 first powersthe pre-charge switch 204 to charge the capacitor 38 (shown in FIG. 1),without powering the main contactor 102. After the capacitor 38 ischarged, the controller 240 turns off the pre-charge switch 204 andpowers the coil assembly 140 to activate the main contactor 102. In anexemplary embodiment, an electrical connector 250 is coupled to thepower distribution unit 100 to supply control or trigger signals to thecontroller 240. For example, the electrical connector 250 is coupled tothe trigger connector 248 (shown in FIG. 3) to electrically connect tothe controller 240. The control signals trigger operation of the powerdistribution unit 100. For example, when the control signal is receivedat the controller 240, the pre-charge operation is initiated and thenthe activation of the main contactor 102 is initiated.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from its scope. Dimensions, types of materials,orientations of the various components, and the number and positions ofthe various components described herein are intended to defineparameters of certain embodiments, and are by no means limiting and aremerely exemplary embodiments. Many other embodiments and modificationswithin the spirit and scope of the claims will be apparent to those ofskill in the art upon reviewing the above description. The scope of theinvention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Moreover, in the following claims, theterms “first,” “second,” and “third,” etc. are used merely as labels,and are not intended to impose numerical requirements on their objects.Further, the limitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. § 112(f), unless and until such claim limitations expresslyuse the phrase “means for” followed by a statement of function void offurther structure.

What is claimed is:
 1. A power distribution unit comprising: a housinghaving walls defining a main cavity and a secondary cavity; a maincontactor received in the main cavity of the housing, the main contactorincluding first and second fixed contacts and a movable contact movablebetween a mated position and an unmated position, the movable contactengaging the first and second fixed contacts to electrically connect thefirst and second fixed contacts in the mated position, the movablecontact being separated from the first and second fixed contacts in theunmated position, the main contactor including a coil assembly energizedto move the movable contact between the unmated position and the matingposition; a pre-charge assembly received in the secondary cavity of thehousing, the pre-charge assembly including a pre-charge resistor and apre-charge switch coupled to the pre-charge resistor; and a controllerreceived in the housing, the controller including a main contactordriver for powering the main contactor, the controller including apre-charge driver for powering the pre-charge switch.
 2. The powerdistribution unit of claim 1, wherein the pre-charge switch is asemiconductor switch.
 3. The power distribution unit of claim 1, whereinthe pre-charge resistor and the pre-charge switch are mounted to acontrol circuit board of the controller.
 4. The power distribution unitof claim 1, wherein the controller includes a microcontroller mounted toa control circuit board, the microcontroller operably coupled to themain contactor driver and operably coupled to the pre-charge driver,wherein the microcontroller activates the pre-charge driver uponreceiving a trigger signal to charge the pre-charge capacitor prior toactivating the main contactor driver.
 5. The power distribution unit ofclaim 1, wherein the controller includes a trigger connectorelectrically coupled to a control circuit board, the trigger connectorconfigured to receive a trigger signal from a vehicle controller, thecontroller including a microcontroller operably coupled to the maincontactor driver and operably coupled to the pre-charge driver, whereinthe microcontroller activates the pre-charge driver upon receiving thetrigger signal to charge the pre-charge capacitor prior to activatingthe main contactor driver.
 6. The power distribution unit of claim 1,wherein the main contactor driver and the pre-charge driver are mountedon a same side of a control circuit board of the controller.
 7. Thepower distribution unit of claim 1, wherein the controller includes apower circuit on a control circuit board, the power circuit beingelectrically connected to the main contactor driver and beingelectrically connected to the pre-charge driver.
 8. The powerdistribution unit of claim 1, wherein the pre-charge assembly includesfirst and second pre-charge connection terminals, the first pre-chargeconnection terminal coupled to the first fixed contact and coupled to acontrol circuit board, the second pre-charge connection terminal coupledto the second fixed contact and coupled to the control circuit board,the first and second pre-charge connection terminals being electricallycoupled to the pre-charge driver, wherein the first and secondpre-charge connection terminals supply power to the control circuitboard for operating the pre-charge driver.
 9. The power distributionunit of claim 8, further comprising coil connecting terminals coupled tothe coil assembly and coupled to the control circuit board, the coilconnecting terminals being electrically coupled to the main contactordriver, the coil connecting terminals supply power to the coil assemblyto activate the main contactor and move the movable contact to the matedposition.
 10. The power distribution unit of claim 8, wherein thehousing includes contact channels passing through one of the walls ofthe housing, the first and second pre-charge connection terminals beingreceived in corresponding contact channels.
 11. The power distributionunit of claim 1, wherein the main contactor driver is operated apredetermined time after the pre-charge driver is operated.
 12. A powerdistribution unit comprising: a housing having walls defining a maincavity and a secondary cavity; a main contactor received in the maincavity of the housing, the main contactor including first and secondfixed contacts and a movable contact movable between a mated positionand an unmated position, the movable contact engaging the first andsecond fixed contacts to electrically connect the first and second fixedcontacts in the mated position, the movable contact being separated fromthe first and second fixed contacts in the unmated position, the maincontactor including a coil assembly energized to move the movablecontact between the unmated position and the mating position; apre-charge assembly received in the secondary cavity of the housing, thepre-charge assembly including a pre-charge resistor and a pre-chargeswitch coupled to the pre-charge resistor and configured to be coupledto a pre-charge capacitor; and a controller received in the housing, thecontroller including a trigger connector electrically coupled to acontrol circuit board, the trigger connector configured to receive atrigger signal from a vehicle controller, the controller including amain contactor driver for powering the main contactor, the controllerincluding a pre-charge driver for powering the pre-charge switch, thecontroller including a microcontroller mounted to the control circuitboard, the microcontroller being operably coupled to the main contactordriver and operably coupled to the pre-charge driver, wherein themicrocontroller activates the pre-charge driver upon receiving thetrigger signal to charge the pre-charge capacitor prior to activatingthe main contactor driver.
 13. The power distribution unit of claim 12,wherein the pre-charge resistor and the pre-charge switch are mounted tothe control circuit board.
 14. The power distribution unit of claim 12,wherein the control circuit board includes a power circuit, the powercircuit being electrically connected to the main contactor driver andbeing electrically connected to the pre-charge driver.
 15. The powerdistribution unit of claim 12, wherein the pre-charge assembly includesfirst and second pre-charge connection terminals, the first pre-chargeconnection terminal coupled to the first fixed contact and coupled tothe control circuit board, the second pre-charge connection terminalcoupled to the second fixed contact and coupled to the control circuitboard, the first and second pre-charge connection terminals beingelectrically coupled to the pre-charge driver, wherein the first andsecond pre-charge connection terminals supply power to the controlcircuit board for operating the pre-charge driver, and wherein the powerdistribution unit further comprises coil connecting terminals coupled tothe coil assembly and coupled to the control circuit board, the coilconnecting terminals being electrically coupled to the main contactordriver, the coil connecting terminals supply power to the coil assemblyto activate the main contactor and move the movable contact to the matedposition.
 16. The power distribution unit of claim 15, wherein thehousing includes contact channels passing through one of the walls ofthe housing, the first and second pre-charge connection terminals beingreceived in corresponding contact channels.
 17. The power distributionunit of claim 12, wherein the main contactor driver is operated apredetermined time after the pre-charge driver is operated.
 18. Avehicle battery system comprising: a high voltage battery pack having apositive battery terminal and a negative battery terminal; an inverterconfigured to convert DC power from the high voltage battery pack to ACpower for operating an electric motor of a vehicle; and a powerdistribution unit between the high voltage battery pack and theinverter, the power distribution unit comprising: a housing having wallsdefining a main cavity and a secondary cavity; a main contactor receivedin the main cavity of the housing, the main contactor including firstand second fixed contacts and a movable contact movable between a matedposition and an unmated position, the movable contact engaging the firstand second fixed contacts to close the main contactor and electricallyconnect the high voltage battery pack with the inverter, the movablecontact being separated from the first and second fixed contacts in theunmated position to open the main contactor, the main contactorincluding a coil assembly energized to move the movable contact betweenthe unmated position and the mating position; a pre-charge assemblyreceived in the secondary cavity of the housing, the pre-charge assemblyincluding a pre-charge resistor and a pre-charge switch coupled to thepre-charge resistor and configured to be coupled to a pre-chargecapacitor; and a controller received in the housing, the controllerconfigured to receive a trigger signal from a vehicle controller, thecontroller including a main contactor driver for powering the maincontactor, the controller including a pre-charge driver for powering thepre-charge switch, the controller including a microcontroller operablycoupled to the main contactor driver and operably coupled to thepre-charge driver, wherein the controller activates the pre-chargedriver upon receiving the trigger signal to charge the pre-chargecapacitor prior to activating the main contactor driver.
 19. The vehiclebattery system of claim 18, wherein the controller includes a powercircuit, the power circuit being electrically connected to the maincontactor driver and being electrically connected to the pre-chargedriver.
 20. The vehicle battery system of claim 18, wherein thepre-charge assembly includes first and second pre-charge connectionterminals, the first pre-charge connection terminal coupled to the firstfixed contact and coupled to the controller, the second pre-chargeconnection terminal coupled to the second fixed contact and coupled tothe controller, the first and second pre-charge connection terminalsbeing electrically coupled to the pre-charge driver, wherein the firstand second pre-charge connection terminals supply power to thecontroller for operating the pre-charge driver, and wherein the powerdistribution unit further comprises coil connecting terminals coupled tothe coil assembly and coupled to the controller, the coil connectingterminals being electrically coupled to the main contactor driver, thecoil connecting terminals supply power to the coil assembly to activatethe main contactor and move the movable contact to the mated position.